Multiple-digit display device and method of manufacturing the same

ABSTRACT

A multiple-digit display device comprising an electrode substrate in which a plurality of sets of cathodes of a desired pattern constituting a plurality of display sections respectively and a plurality of sets of anodes associated with the plural sets of cathodes respectively are multilevel-printed on a dielectric substrate through dielectric layers, and a front plate provided on the electrode substrate so as to form a plurality of discharge spaces on the plural display sections, and a method of manufacturing the multiple-digit display device.

United States Patent Miyamoto et a1.

MULTIPLE-DIGIT DISPLAY DEVICE AND METHOD OF MANUFACTURING THE SAME Inventors: Akio Miyamoto; Masaharu Koyama,

both of Mobara; Toyokazu Odaka, Chiba; Kanji Otsuka; Gen Murakami, both of Kodiara, all of Japan Assignee: Hitachi, Ltd., Tokyo, Japan Filed: May 31, 1973 Appl. No.: 365,404

Foreign Application Priority Data June 1, 1972 Japan 47-54617 US. Cl. 316/20, 313/514 Int. Cl. H0lj 9/38 Field of Search 3l3/109.5, 210, 220;

315/169 R, 169 TV; 316/17, 18, 19, 20

References Cited UNITED STATES PATENTS 10/1966 Greene 313/l09.5 3/1969 Vodicka 313/109.5

[ 1 Mar. 25, 1975 3,504,214 3/1970 Lake 313/1095 3,588,571 6/1971 Vemura 315/169 TV 3,646,384 2/1972 Lay 313/220 3,684,918 8/1972 Schmersal 315/169 TV 3,701,918 10/1972 Allen 315/169 TV 3,737,707 6/1973 Yanagisawa.. 313/109.5 3,754,161 8/1973 Johnson 315/169 TV 3,764,429 10/1973 Janning 313/l09.5

Primary Examiner-James W. Lawrence Assistant Examiner-D. C. Nelms Attorney, Agent, or Firm-Craig & Antonelli [57] ABSTRACT A multiple-digit display device comprising an electrode substrate in which a plurality of sets of cathodes of a desired pattern constituting a plurality of display sections respectively and a plurality of sets of anodes associated with the plural sets of cathodes respectively are multilevel-printed on a dielectric substrate through dielectric layers, and a front plate provided on the electrode substrate so as to form a plurality of dis charge spaces on the plural display sections, and a method of manufacturing the multiple-digit display device.

13 Claims, 11 Drawing Figures PATENTEDHARZ I975 SI'LET 3 UF 4 FlG.2 e I OCJOOOOOOOGOQOOO I] II! I I 32 g uuuuu OOOOOOOx-l. 17b

F|G.2g 0000 UHUIJUHUUHIJUHUHUUUUUUH MULTIPLE-DIGIT DISPLAY DEVICE AND METHOD OF MANUFACTURING THE SAME cRoss REFERENCE TO RELATED APPLICATIONS The present application relates to subject matter described in application Ser. No. 365,440 filed May 31, 1973, entitled Multiple Digit Display Device and Method of Manufacturing Same by Akio Miyamoto, Masaharu Koyama, Toyokazu Odaka, Kanji Otsuka and Gen Murakami, and assigned to the assignee of the present application, and it relates to the subject matter described in application Ser. No. 365,405, filed May 31, 1973, entitled Multiple-Digit Display Device," by Akio Miyamoto, Masaharu Koyama, Toyokazu Odaka and also assigned to the assignee of the present applica tion.

This invention relates to a multiple-digit display de vice for displaying a plurality of desired patterns such as figures, characters and symbols in a juxtaposed state by means of gaseous discharge and a method of manufacturing such a display device.

In a multiple-digit display device of the kind utilizing a gaseous discharge for display, a plurality of display sections each including a plurality of display cathodes arranged according to a desired pattern and a plurality of anodes associated with these display cathodes are juxtaposed within the same envelope so that the desired pattern can be displayed in response to the application of voltage across selected ones of the display cathodes and selected ones of the anodes and this multiple-digit pattern display can be attained by controlling the device in time division fashion.

Multiple-digit display devices of various structures have been proposed hitherto, but none of them have been completely satisfactory. For example, according one of the prior art proposals, cathodes, cathode leads, etc., are formed on a sintered dielectric substrate by means of multilevel-printing, and preformed elements such as anodes and partition walls for individual digits are mechanically secured to the dielectric substrate. However, due to the fact that the preformed individual anodes are connected as by welding to lead wires in the apertures bored in the dielectric substrate in such a prior art structure, this multiple-digit display device is not suitable for mass production and the reliability of the electrical connection is low. Further, there is a structural limitation in the desired reduction of the thickness of the display device. Furthermore, due to the fact that the cathodes and anodes are disposed opposite to each other through a discharge space, the displayed pattern is observed through the anodes, and thus, the anodes must be of meshed structure or of transparent material. However, the use of the meshed anodes is defective in that not only the display is difficult to observe but also the number of necessary parts is greatly increased. The use of the transparent anodes in the form ofa film of NESA (a trade-mark) is also defective in that the transparent film electrode may be damaged by the heat produced during sealing.

It is therefore an object of the present invention to provide a multiple-digit display device in which a multilevel wiring technique and a plug-in system are employed for eliminating the problem of electrical connection with external circuits and which can therefore be easily manufactured at low cost.

Another object of the present invention is to provide a multiple-digit display device which has a very small thickness by virtue of the fact that electrodes and wires are deposited on a single substrate by means of multilevel-printing,

Still another object of the present invention is to provide a multiple-digit display device which can be very easily manufactured by virtue of the fact that electrodes and wires are formed on a single unsintered substrate by means of multilevel-printing.

A further object of the present invention is to provide a multiple-digit display device in which the number of necessary parts is less than heretofore and which is suitable for mass production.

In accordance with one aspect of the present invention, there is provided a multiple-digit display device comprising an electrode substrate in which a plurality of sets of cathodes of desired pattern constituting a plurality of display sections respectively and a plurality of sets of anodes associated with said plural sets of cathodes respectively are multilevel-printed on a dielectric substrate through dielectric layers, a partition plate disposed on said electrode substrate and having a plurality of spaced openings corresponding individually to said display sections so as to define the respective discharge spaces containing a discharge medium, and a front plate disposed on said partition plate and transparent at least at those portions opposite to the respective display sections, the outer periphery of the laminate structure consisting of said electrode substrate, said partition plate and said front plate being sealed gastight.

In accordance with another aspect of the present invention, there is provided a method of manufacturing a multiple-digit display device comprising the steps of forming an electrode substrate by multilevel-printing on a dielectric substrate through dielectric layers a plurality of sets of cathodes of predetermined pattern constituting a plurality of display sections respectively and a plurality of sets of anodes associated with said plural sets of cathodes respectively, disposing on said electrode substrate a partition plate having a plurality of spaced openings corresponding individually to said display sections so as to define respective discharge spaces, disposing on said partition plate a front plate which is transparent at least at those portions opposite to the respective display sections, sealing gastight the outer periphery of the laminate structure consisting of said electrode substrate, said partition plate and said front plate, and evacuating said laminate structure and introducing a discharge medium into said discharge spaces.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic exploded perspective view of a multiple-digit display device embodying the present invention;

FIGS. 2a to 2h show schematically successive steps for the manufacture of the multiple-digit display device shown in FIG, 1; I

FIG. 3 is a schematic enlarged plan view showing one of the display sections in the multiple-digit display device manufactured by the method shown in FIGS. 2a to 2h; and

FIG. 4 is a schematic sectional view taken on the line IV-lV in FIG. 3.

FIG. '1 is a schematic exploded perspective view of an embodiment of the present invention and this multipledigit display device is constructed to display, for example, thirteen digits. Referring to FIG. 1, the multipledigit display device comprises a rectangular front plate 1 of transparent material such as glass (hereinafter referred to as a transparent plate), a partition plate 2 having a plurality of spaced independent openings corre sponding individually to the digits or display sections so as to partition the digits or display sections from each other and an electrode substrate 3. This electrode substrate 3 includes a plurality of sets of display cathodes 4 with each set disposed in the form of E (8), a plurality of pairs of spaced inner anodes 5 with each pair disposed within the zones defined by each set of these cathodes 4 so as to be surrounded by the latter, a plurality of outer anodes 6 each disposed outside of each set of these cathodes 4 so as to surround the latter, a plurality of auxiliary electrodes 6 for indicating the decimal point, a plurality of terminals 8 serving as external connection means for the display cathodes 4, inner and outer anodes 5 and 6 and auxiliary electrodes 7, and many wires (not shown) for electrically connecting these electrodes to the terminals 8. The electrode substrate 3 including these electrodes, terminals and wires is formed by means of multilevel-printing of a conductive material on a dielectric substrate. Other display sections for displaying symbols such as plus and minus may of course be provided on the electrode substrate 3, but such display sections are not shown herein for conveniences of description and illustration. Further, the transparent plate 1 may be transparent at least at those portions opposite to the display sections.

The transparent plate 1, partition plate 2 and elec trode substrate 3 having such a structure are successivcly laminated, and this laminated structure is sealed gastight at the outer periphery thereof with a sealing material such as a low-melting glass, organic binder, special brazing material or solder. After evacuating the interior of the laminated structure, a discharge medium which may be a rare gas such as neon or argon or their mixture is enclosed within the discharge spaces of the laminated structure to provide the multiple-digit display device.

When voltage is applied across the terminals 8 connected to selected ones of the display cathodes 4 and the terminals 8 connected to the inner and outer anodes 5 and 6 in the multiple-digit display device having such a structure, discharge occurs between the selected display cathodes 4 and the inner and outer anodes 5 and 6, and the display cathodes 4 provides illumination of desired pattern. Due to the fact that the corresponding display'cathodes 4 (hereinafter referred to as'common cathodes) in the respective display sections are connected in common to the same terminals 8 as will be described later, desired patterns can be displayed on the individual display sections by successively selecting and applying voltage in time division fashion to the terminals 8 connected to the inner and outer anodes 5 and 6 in the individual display sections independently of one another.

Further, the multiple-digit display device according to the present invention requires a very small number of necessary parts compared with prior art devices, has a very small overall thickness and is suitable for mass production due to the fact that it is composed of only three members, that is, the transparent plate 1, partias butylcarbitol acetate are added to a powdery eeramic material consisting essentially of, for example, aluminum oxide having a purity higher than 90 percent toobtain a pasty composition. This pasty composition is shaped into a sheet form about 2 mm thick and is then dried to obtain an unsintered dielectric sheet in the form of a strip or ribbon (hereinafter referred to as a green sheet) as shown in FIG. 20. Many jig receiving holes 10 are bored along the opposite sides of this green sheet for the purpose of ensuring correct positioning of the sheet in the later steps, thereby obtaining an unsintered dielectric substrate 11.

Then, as shown in FIG. 2b, a conductive material is deposited by a screen printing technique on the surface of the unsintered dielectric substrate 11 for forming cathode terminals 12a to 1211, wires 13a to 13/1 extending in the longitudinal direction of the substrate 11 for connection between common cathodes, wires 14a and 14b to be connected to anodes, cathode lead wires 15, connection points 16a to 16h positioned at the end of the cathode lead wires 15, anode terminals 17a to 17m, anode lead wires 34, and connection points 21 positioned at the end of the anode lead wires 34. The wire 13h in FIG. 2b is provided for connection between the auxiliary electrodes 7 indicating the decimal point shown in FIG. 1. The conductive material is applied in powder form and may be a conductive highmelting metal such as tungsten (W), molybdenum (Mo), manganese (Mn), titanium (Ti) or platinum (Pt) or a mixture of some of these metals. The conductive material may also be a conductive paste consisting of a powdery oxide of such metal, a binder such as polyvinylbutyral and a solvent such as butylcarbitol acetate. The unsintered dielectric substrate 11 having the above pattern printed with the conductive material is then subjected to drying in air at about C for about 15 minutes so that the conductor layer'can be firmly secured to the surface of the unsintered dielectric substrate 11.

Then, as shown in FIG. 21' a first dielectric layer 18 is printed on the unsintered dielectric substrate 11 shown in FIG. 2b. In this case, the first dielectric layer 18 is deposited by screen printing on the central portion of the substrate 1 1 except the portions corresponding to the cathode connection points 19 and connection points 23a to 23h on the wires 13a to 13!: serving as the connection paths for the common cathodes, anode connection points 20 positioned at the opposite ends of the wires 14a and 14b to be connected to the anodes, connection points 16a to 16h positioned at the end of the cathode lead wires 15, connection points 21 positioned at the end of the anode lead wires 34, cathode terminals 12a to 12h, and anode terminals 17a to 17m. These connection points have a diameter of, for example, about 0.3 to l.O mm, and thus, the holes therefor can be very easily formed by screen printing.

The first dielectric layer 18 is about p. to 0.5 mm thick and is thus very thin compared with the diameter of the holes at the connection points. This first dielectric layer 18 may be formed from a material similar to that employed for forming the unsintered dielectric substrate 11. However, in order to provide a viscosity suitable for printing and to obviate possible occurrence of pinholes, it is preferable to employ a composition consisting of, for example, 50 percent by weight of a powdery ceramic material consisting essentially of aluminum oxide, 20 percent by weight of polyvinylbutyral or cetyl cellulose which is a binder possessing the adhesiveness suitable for printing, and 30 percent by weight of butylcarbitol acetate which is a solvent giving the required viscosity.

The unsintered dielectric substrate 11 having the first dielectric layer 18 printed thereon is subsequently dried under a condition similar to that described with reference to FIG. 212. Then, as shown in FIG. 2d, a conductive material similar to that described hereinbefore is deposited on the first dielectric layer 18 by screen printing to provide cathodes 22 slightly spaced from the cathode connection points 19 and connected partly to the respective cathode connection points 19, and cathode lead wires 24 disposed between the connection points 16a to 16/1 and the connection points 23a to 23/1 lying on the wires 13a to 13h serving as the connection paths for the common cathodes respectively. During this screen printing,auxiliary electrodes 32 are provided and wires 33 for connecting the auxiliary electrodes 32 to the connection points 19 lying on the wire 13h are also provided. Due to the fact that the thickness of the first dielectric layer 18 is very small conipared with the diameter of the holes at the connection points, the conductive material applied to the first dielectric layer 18 flows readily into these holes during the screen printing so that the conductive layer can be easily and reliably electrically connected to the underlying conductive layer through the first dielectric layer 18. In FIG. 2d, the holes at the connection points 19, 23a to 23h and 16a to 16h are filled with the conductive material. In the state shown in FIG. 2d, therefore, the common cathodes 22 are electrically connected to the wires 13a to 13!: through the cathode connection points 19 respectively, and the wires 13a to 13/1 are electrically connected to the cathode terminals 12a to 1211 through the connection points 23a to 2311, cathode lead wires 24, connection points 16a to 16/1 and cathode lead wires respectively. The cathodes 22 are deposited in slightly spaced relation from the connection points 19 because deposition of the cathodes 22 on the connection points 19 may produce unevenness on the cathode surface resulting in non-uniform luminescence.

Then, as shown in FIG. 22, a second dielectric layer 25 is printed on the first dielectric layer 18 in a manner similar to that described hereinbefore. This second dielectric layer 25 is deposited on the portions except the portions corresponding to the cathodes 22, connection points 20 positioned at the opposite ends of the wires 14a and 14b to be connected to the anodes, connection points 21 for the anode terminals 17a to 17m, and auxiliary electrodes 32 connected to one end of the wires 33.

Then, as shown in FIG. 2f, a conductive material similar to that described hereinbefore is used to print on the second dielectric layer 25 a plurality of pairs of inner anodes 26 with each pair disposed in the respective zones surrounded by the cathodes 22 in each dis play section, a plurality of outer anodes 27 each surrounding the cathodes 22 in each display section and connected partly to the connection point 20, and wires 28 disposed between the outer anodes 27 and the connection points 21 for the anode terminals 17a to 17m. During this printing step, the holes at the connection points 21 are filled with the conductive material and the inner anodes 26 are printed to fill the holes at the connection points 20 lying within the zones surrounded by the cathodes 22. The printed conductor layer is then dried under a condition similar to that described with reference to FIG. 2b. In the state shown in FIG. 2f, therefore, the inner and outer anodes 26 and 27 in each display section are connected in common to one another by the connection points 20 and wires 14 a and 14b thereby constituting a single anode, and these single anodes in the individual display sections are connected to the anode terminals 17a to 17m by the wires 28, connection points 21 and wires 34 respectively.

Then, as shown in FIG. 2g, a dielectric material is printed on all the portions of the second dielectric layer 25 except the portions corresponding to the cathodes 22, inner and outer anodes 26 and 27, and auxiliary electrodes 32 so as to provide a third dielectric layer 29, that is, the outermost dielectric layer in the present embodiment. The dielectric material employed for forming this third dielectric layer 29 may be similar to that employed for forming the first and second dielectric layers I8 and 25. In such a case, however, light from the light-emitting cathodes may be scattered by the display surface and the display effect may be reduced due to the fact that these dielectric layers are generally white in color. In order to solve such a problem, the third dielectric layer 29, that is, the outermost dielectric layer should have a color which provides less reflection of light. When, for example, titanium oxide is added to the powdery ceramic material consisting essentially of aluminum oxide, the dielectric layer thus obtained, is grey or black in color depending on the content of titanium oxide. The dielectric layer is purple in color when cobalt oxide is added to the ceramic material, while it becomes pinkish or blackish when manganese dioxide is added to the ceramic material.

The multilevel-printed unsintered substrate 11 shown in FIG. 2g is then suitably trimmed at end edges thereof to obtain an unsintered electrode substrate 30 as shown by the two-dot chain lines in FIG. 2h. The unsintered electrode substrate 30 thus obtained is then placed and held in a non-oxidizing atmosphere at about I,400C to l,650C for about 1 hour. As a result of this sintering treatment, the unsintered substrate 11 consisting essentially of aluminum oxide, and the dielectric layers and conductive layers formed by printing are simultaneously sintered to provide an electrode substrate 30 as shown by the solid lines in FIG. 2h. During this sintering step, the additives such as the binder and solvent in the dielectric and conductive materials are evaporated or ignited resulting in a reduction by about 15 percent of the original dimensions of the unsintered electrode substrate 30. The electrode substrate 31 having prede termined dimensions can be obtained by suitably sizing the unsintered electrode substrate 30 taking into consideration the reduction of the dimensions due to sintering.

A partition plate for defining the display sections is disposed on the electrode substrate 31 thus obtained and then a transparent plate is disposed on the partition plate to form a laminate. A sealing material such as a low-melting plass is applied to the outer periphery of this laminate and the laminate is heated at a temperature of about 420C to 550C for about 1 hour to be sealed gastight at the outer periphery thereof. A discharge medium is then enclosed in the discharge spaces of the laminate to complete a multiple-digit display de- VICE.

The method shown in FIGS. 2a to 211 is merely illustrative of one form of the present invention and various changes and modifications maybe made therein. For example, the wires 13a to 13h for connection between the common cathodes in FIG. 2); may be directly connected to the cathode terminals 12a to 1211 so as to eliminate the cathode lead wires 24 shown in FIG. 2d. Further, the connection points 21 in FIG. 212 may be directly disposed on the anode terminals 17a to 17m so as to eliminate the anode lead wires 34.

FIG. 3'is a schematic enlarged plan view of one-of the display sections of the electrode substrate 31 manufactured by the method described with reference to FIGS. 2a to 2h, and FIG. 4 is a schematic section view taken on the line IVIV in FIG. 3. In FIGS. 3 and 4, the same reference numerals are used to denote the same parts shown in FIGS. 2a to 211. Referring to FIGS. 3 and 4, the first conductive layer in the electrode substrate 31 obtained by the method of the present invention includes the anode terminals 17a to 17m for external connection, cathode terminals 12a to 1211, wires 13a to 13h for connection between the common cathodes, common connection wires 14a and 14b for the inner and outer anodes 26 and 27, and cathode lead wires 15. The first dielectric layer 18 is printed on this first conductive layer except the portions corresponding to the required connection points. The second conductive layer is printed on this first dielectric layer 18 and includes the cathodes 22 (22a to 22h), and wires connected at one end thereof to the cathodes 22 (22a to 22h) and at the other end thereof to the wires 13a to 13h in the first conductive layer through the connection points in the first dielectric layer 18. The cathodes 22 may have an uneven surface when the connection points are disposed directly on the cathode portions for connecting the cathodes 22 to the first conductive layer without providing the lead 'wires for connecting the cathodes 22 to the first conductive layer. In the display of this kind utilizing gaseous discharge, light is emitted from the cathodes, and thus, presence of slight unevenness on the cathode surface results in non-uniform luminescence. In the present invention, the second dielectric layer 25 is disposed on the second conductive layer except the portions corresponding to the oathodes 22 and required connection points. This second dielectric layer 25 is provided for covering the connection points for the cathodes so that the anodes can be disposed in the vicinity of the cathodes in substantially coplanar relation with the cathodes. In order to provide the anodes without employing the second dielectric layer 25, the anodes must be sufficiently spaced from the cathodes or the anodes must be directly disposed on the first conductive layer. However, in the former case, a degree of structural freedom is lost thereby greatly adversely affecting the electrical properties of the display device, while in the latter case, discharge is made with difficulty. The-third conductivelayer is disposed on the second dielectric layer 25 and-includes the inner and outer anodes 26 and 27, wires 28 for connecting the anodes 26 and 27 to the anode terminals 17a to 17m, and wires 14a and 14b for connection between these anodes. The third dielectric layer 29 is then printed on this third conductive layer except that the portions corresponding to the cathodes and anodes.

Multilevel-printing is required so that anodes and cathodes for the display of desired patterns such as figures, characters or symbols and wires for connecting these electrodes to external circuits can be provided on a single dielectric substrate, and this is done by repeatedly printing a plurality of conductive layers and dielectric layers on the single dielectric substrate. An electrode substrate having a complex structure can be obtained by increasing the number of printing, hence the number of layers. At least three conductive layers and three dielectric layers are required in order to provide at least two kinds of electrodes with good efficiency and without deteriorating the desired display effect. An attempt to dispose the anodes on the first dielectric layer and to dispose the cathodes on the second dielectric layer results in the loss of the degree of structural freedom of either the anodes or the-cathodes. Therefore, the best effect can be obtained with the smallest number of steps when the cathodes are disposed on the first dielectric layer and the anodes are disposed on the second dielectric layer. The electrode substrate thus obtained can be used in that form as a part of the display device utilizing gaseous discharge. However, it is preferable to plate a metal such as nickel on the electrodes for smoothing the electrode surface thereby ensuring uniform luminescence. Further, in the gaseous discharge display device having the structure above described, a stabilizing resistor having a resistance of about 10 to 200 kilohms is commonly connected to each electrode for stabilizing the discharge. In the present embodiment, a portion or entirety of the cathode lead wires 15 in FIG. 2b and/or cathode lead wires 24 in FIG. 2d, and anode lead wires 34 in FIG. 212 and/or anode lead wires 28 in FIG. 2f may be formed by a resistor. This is advantageous in that the number of circuit elements is remarkably reduced due to the fact that the stabilizing resistors are incorporated in the electrode substrate. In the present embodiment, the display electrodes or cathodes have been printed in the pattern corresponding to the desired display pattern in FIG. 2a to 2h. However, due to the fact that the second dielectric layer is disposed on the second conductive layer including these display cathodes therein, the shape of the cathodes themselves may not be limited in any way and the shape of the portions of the cathodes exposed from the second dielectric layer may be selected to correspond to the desired display pattern for attaining the effect similar to that above described. The sealing material employed in sealing gastight the outer periphery of the laminate composed of the transparent plate, partition plate and electrode substrate is preferably a lowmelting glass as pointed out hereinbefore since the application of high temperatures to the laminate will result in oxidation of the electrode surface due to heat, and hence non-uniform luminescence will result.

The embodiment of the present invention has been described with reference to the use of an unsintered dielectric substrate made of a ceramic material consisting essentially of aluminum oxide by way of example. However, the present invention is in no way limited to such a substrate, and an' unsintered green sheet made of a powdery dielectric material such as powdery forsterite or powdery glass may be used.

It will be understood from the foregoing detailed description that the multiple-digit display device and the method of manufacturing such a display device according to the present invention are advantageous in that the display device has a very small thickness and electrical connections between the electrodes and the wires can be very easily and reliably attained since the cathodes and anodes are disposed in substantially coplanar relation. Further, in the present invention the electrode substrate having all the required electrodes and wires therein is formed by multilevel-printing. The present invention is advantageous in that the conventional step for the punching of interconnecting holes is unnecessary, and thus, the electrode substrate can be formed very simply and reliably. Furthermore, the present in vention is advantageous in that the dielectric material and conductive material can be economically and effectively used due to the fact that the thickness of the dielectric layers and conductive layers can be freely varied by varying the amount of the paste used in printing. Moreover, the present invention is advantageous in that the manufacturing process can be remarkably simplified and the positioning and electrical connections of the electrodes and wires can be reliably attained due to the fact that the electrode substrate is formed by depositing the electrodes, wires and terminals on an unsintered green sheet by multilevel-printing and then simultaneously sintering these elements. Further, the present invention in which the cathodes and anodes are disposed in substantially coplanar relation is advantageous in that light emitted from the cathodes is not intercepted by the anodes and the pattern can be displayed more clearly than heretofore. The multiple-digit disi play device according to the present invention can be obtained by merely laminating the partition plate and transparent plate on the electrode substrate provided with the cathodes and anodes so as to form the discharge spaces in the laminate and then sealing gastight the outer periphery of the laminate. Thus, it is an additional advantage of the present invention that the number of required parts is remarkably smaller than heretofore and the display device can be very easily assembled.

What we claim is:

ll. Amethod of forming an electrode substrate for a multiple-digit display device in which cathodes and anodes are arranged in a single substrate, comprisingthe steps of:

a. shaping a pasty composition comprising a dielectric material, a binder and a solvent into a sheet form of a predetermined thickness and size;

b. drying the sheet to obtain an unsintered dielectric sheet;

c. multilevel-printing, on said unsintered dielectric sheet, a plurality of sets of cathodes for respective digits, a plurality of sets of anodes associated respectively with said cathode sets, a plurality of cathode terminals for the corresponding cathodes between said cathode sets, a plurality of anode terminals for said anode sets, a plurality of wires for the connection of the corresponding cathodes, between said cathode sets, to said cathode terminals, a plurality of wires for the connection of said anode sets to said anode terminals, and a plurality of dielectric layers to provide an unsintered multilayer electrode structure; and 1 d. sintering said unsintered multilayer electrode structure to provide an electrode substrate.

2. A method according to claim 1, wherein a resistor is incorporated in at least a portion of selected ones of said wires.

3. A method according to claim 1, wherein said step (c) comprises the steps of:

cl. printing, on said unsintered dielectric sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals;

c2. printing, on the structure resulting from step (cl), a first dielectric layer having predetermined holes therethrough;

c3. printing, on the structure resulting from step (c2), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes;

c4. printing a second dielectric layer on the structure resulting from step (c3), exposing said cathode sets;

c5. printing, on the structure resulting .from step (04), said anode sets and third wires connected thereto and to be connected respectively to said anode terminals; and

c6. printing a third dielectric layer on the structure resulting from step (c5), exposing said cathode sets and said anode sets.

4. A method of manufacturing a multiple-digit gaseous discharge display device comprising the steps of:

i. preparing an electrode substrate by a. shaping a pasty composition comprising a dielectric material, a binder and a solvent into a sheet form of a predetermined thickness and size,

b. drying the sheet to an unsintered dielectric sheet,

c. multilevel printing, on said unsintered dielectric sheet, a plurality of sets of cathodes for respective digits, a plurality of sets of anodes associated respectively with said cathode sets, a plurality of cathode terminals for the corresponding cathodes between said cathode sets, a plurality of anode terminals for said anode sets, a plurality of wires for the connection of the corresponding cathodes between said cathode sets to said cathode terminals, a plurality of wires for the connection of said anode sets to said anode terminals, and aplurality of dielectric layers to provide an unsintered multilayer electrode structure, and

d. sintering said unsintered multilayer electrode 7 structure; ii. locating, on said electrode substrate, a partition plate having a plurality of spaced openings corresponding individually to the display sections of said electrode substrate including respectively said cathode sets therein so as to define respective discharge spaces; 7 iii. locating, on said partition plate, a front plate which is transparent at least at those portions opposite to the respective display sections;

iv. sealing gastight the outer periphery of the laminate structure consisting of said electrode substrate, said partition plate and said front plate; and

v. evacuating said laminate structure and introducing a discharge medium into said discharge spaces.

5. A method according to claim 4, wherein a resistor is incorporated in at least a portion of selected ones of said wires.

6. A method according to claim 4, wherein said step i (c) comprises:

icl. printing, on said unsintered dielectric sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals;

ic2. printing, on the structure resulting from step i (cl), a first dielectric layer having predetermined holes therethrough;

ic3. printing, on the structure resulting from step i (c2), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes;

ic4. printing a second dielectric layer on the structure resulting from step i (c3), exposing said cathode sets;

ic5. printing, on the structure resulting from step i(c4) said anode sets and third wires connected thereto and to be connected respectively to said anode terminals; and

ic6. printing a third dielectric layer on the structure resulting from step i (05), exposing said cathode sets and said anode sets.

7. In a method of manufacturing a multiple-digit display device including a single substrate having a plurality of cathodes and anodes arranged thereon, an improved method of forming said substrate having said cathodes and anodes arranged thereon, comprising the steps of:

a. multilevel-printing, on an unsintered dielectric sheet, a plurality of sets of cathodes for respective digits tobe included in said display device, a plurality of sets of anodes associated respectively with said cathode sets, a plurality of cathode terminals to be connected to respective cathodes of said cathode sets, a plurality of anode terminals to be connected to respective anodes of said anode sets, a plurality of wires for interconnecting said cathode terminals to said cathodes, a plurality of wires for interconnecting said anode terminals to said anodes, and a plurality of unsintered dielectric layers, to thereby provide an unsintered multilayer electrode structure; and

b. sintering said multilayer electrode structure to provide a sintered electrode substrate.

8. An improved method according to claim 7,

wherein step (a) comprises the preliminary steps of:

al. shaping a pasty composition of a dielectric material, a binder and a solvent into a sheet having a predetermined size and thickness, and u a2. drying said sheet to obtain said unsintered dielectric sheet.

9. An improved method according to claim 7,

wherein said step (a) comprisesthe steps of:

al. printing, on said unsintered dielectric sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals; a2. printing, on the structure resulting from step (a1), a first. dielectric layer having predetermined holes therethrough'; a3. printing, on the structure resulting from step (a2), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes; a4. printing a second dielectric layer on the structure resulting from step (a3), exposing said cathode sets; a5. printing, on the structure resulting from step a4, said anode sets and third wires connected thereto and to be connected respectively to said anode terminals; and a6. printing a third dielectric layer on the structure resulting from step (a5 exposing said cathode sets and said anode sets. 10. An improved method according to claim 8, wherein step (a) further comprises the steps of:

a3. printing, on said unsintered dielectric sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals; a4. printing, on the structure resulting from step (a3), a first dielectric layer having predetermined holes therethrough; a5. printing, on the structure resulting from step (a4), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes; a6. printing a second dielectric layer on the structure resulting from step (a5), exposing said cathode sets; a7. printing, on the structure resulting from step (a6), said anode sets and third wires connected thereto and to be connected respectively to said anode terminals; and a8. printing a third dielectric layer on the structure resulting from step (a7 exposing said cathode sets and said anode sets. 1 1. A method of manufacturing a multiple-digit gaseous discharge display device comprising the steps of:

a. forming an electrode substrate on which cathodes and anodes are arranged by al. multilevel-printing, on an unsintered dielectric sheet, a plurality of sets of cathodes for respective digits to be included in said display device, a plurality of sets of anodes associated respectively with said cathode sets, a plurality of cathode terminals to be connected to respective cathodes of said cathode sets, a plurality of anode terminals to be connected to respective anodes of said anode sets, a plurality of wires for interconnecting said cathode terminals to said cathodes, a plurality of wires for interconnecting said anode terminals to said anodes, and a plurality of unsintered dielectric layers, to thereby provide an unsintered multilayer electrode structure; and

a2. sintering said multilayer electrode structure to provide a sintered electrode substrate;

b. locating, on said electrode substrate, a partition plate having a plurality of spaced openings corresponding individually to the display sections of said electrode substrate including respectively said cathode sets therein so as to define respective discharge spaces;

c. locating, on said partition plate, a front plate which is transparent at least at those portions opposite to the respective display sections;

d. sealing gastight the outer periphery of the laminate structure consisting of said electrode substrate, said partition plate and said front plate; and

e. evacuating said laminate structure and introducing a discharge medium into said discharge spaces.

12. An improved method according to claim 11,

wherein said step (a1) comprises the steps of:

al -i. printing, on said unsintered dielectric sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals;

al-ii. printing, on the structure resulting from step' (al-i), a first dielectric layer having predetermined holes therethrough;

al-iii. printing, on the structure resulting from step (al-ii), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes;

al-iv. printing a second dielectric layer on the struc ture resulting from step (al-iii), exposing said cathplay device comprising the steps of:

formingan electrode substrate by multilevel-printing, on a dielectric substrate through dielectric layer, a plurality of sets of cathodes of predetermined pattern constituting a plurality of display sections respectively and a plurality of sets of anodes associated with said plural sets of cathodes respectively;

disposing, on said electrode substrate, a partition plate having a plurality of spaced openings corresponding individually to said display sections so as to define the respective discharge spaces;

disposing, on said partition plate, a front plate which is transparent at least at those portions opposite to the respective display sections;

sealing gastight the outer periphery of the laminate structure consisting. of said electrode substrate, said partition plate and said front plate;

evacuating said laminate structure and introducing a discharge medium into said discharge spaces; and

wherein said dielectric substrate and said dielectric layers are initially unsintered and are simultaneously sintered before the evacution of said laminate structure. 

1. A method of forming an electrode substrate for a multipledigit display device in which cathodes and anodes are arranged in a single substrate, comprising the steps of: a. shaping a pasty composition comprising a dielectric material, a binder and a solvent into a sheet form of a predetermined thickness and size; b. drying the sheet to obtain an unsintered dielectric sheet; c. multilevel-printing, on said unsintered dielectric sheet, a plurality of sets of cathodes for respective digits, a plurality of sets of anodes associated respectively with said cathode sets, a plurality of cathode terminals for the corresponding cathodes between said cathode sets, a plurality of anode terminals for said anode sets, a plurality of wires for the connection of the corresponding cathodes, between said cathode sets, to said cathode terminals, a plurality of wires for the connection of said anode sets to said anode terminals, and a plurality of dielectric layers to provide an unsintered multilayer electrode structure; and d. sintering said unsintered multilayer electrode structure to provide an electrode substrate.
 2. A method according to claim 1, wherein a resistor is incorporated in at least a portion of selected ones of said wires.
 3. A method according to claim 1, wherein said step (c) comprises the steps of: c1. printing, on said unsintered dielectric sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals; c2. printing, on the structure resulting from step (c1), a first dielectric layer having predetermined holes therethrough; c3. printing, on the structure resulting from step (c2), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes; c4. printing a second dielectric layer on the structure resulting from step (c3), exposing said cathode sets; c5. printing, on the structure resulting from step (c4), said anode sets and third wires connected thereto and to be connected respectively to said anode terminals; and c6. printing a third dielectric layer on the structure resulting from step (c5), exposing said cathode sets and said anode sets.
 4. A method of manufacturing a multiple-digit gaseous discharge display device comprising the steps of: i. preparing an electrode substrate by a. shaping a pasty composition comprising a dielectric material, a binder and a solvent into a sheet form of a predetermined thickness and size, b. drying the sheet to an unsintered dielectric sheet, c. multilevel printing, on said unsintered dielectric sheet, a plurality of sets of cathodes for respective digits, a plurality of sets of anodes associated respectively with said cathode sets, a plurality of catHode terminals for the corresponding cathodes between said cathode sets, a plurality of anode terminals for said anode sets, a plurality of wires for the connection of the corresponding cathodes between said cathode sets to said cathode terminals, a plurality of wires for the connection of said anode sets to said anode terminals, and a plurality of dielectric layers to provide an unsintered multilayer electrode structure, and d. sintering said unsintered multilayer electrode structure; ii. locating, on said electrode substrate, a partition plate having a plurality of spaced openings corresponding individually to the display sections of said electrode substrate including respectively said cathode sets therein so as to define respective discharge spaces; iii. locating, on said partition plate, a front plate which is transparent at least at those portions opposite to the respective display sections; iv. sealing gastight the outer periphery of the laminate structure consisting of said electrode substrate, said partition plate and said front plate; and v. evacuating said laminate structure and introducing a discharge medium into said discharge spaces.
 5. A method according to claim 4, wherein a resistor is incorporated in at least a portion of selected ones of said wires.
 6. A method according to claim 4, wherein said step i (c) comprises: ic1. printing, on said unsintered dielectric sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals; ic2. printing, on the structure resulting from step i (c1), a first dielectric layer having predetermined holes therethrough; ic3. printing, on the structure resulting from step i (c2), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes; ic4. printing a second dielectric layer on the structure resulting from step i (c3), exposing said cathode sets; ic5. printing, on the structure resulting from step i(c4) said anode sets and third wires connected thereto and to be connected respectively to said anode terminals; and ic6. printing a third dielectric layer on the structure resulting from step i (c5), exposing said cathode sets and said anode sets.
 7. In a method of manufacturing a multiple-digit display device including a single substrate having a plurality of cathodes and anodes arranged thereon, an improved method of forming said substrate having said cathodes and anodes arranged thereon, comprising the steps of: a. multilevel-printing, on an unsintered dielectric sheet, a plurality of sets of cathodes for respective digits to be included in said display device, a plurality of sets of anodes associated respectively with said cathode sets, a plurality of cathode terminals to be connected to respective cathodes of said cathode sets, a plurality of anode terminals to be connected to respective anodes of said anode sets, a plurality of wires for interconnecting said cathode terminals to said cathodes, a plurality of wires for interconnecting said anode terminals to said anodes, and a plurality of unsintered dielectric layers, to thereby provide an unsintered multilayer electrode structure; and b. sintering said multilayer electrode structure to provide a sintered electrode substrate.
 8. An improved method according to claim 7, wherein step (a) comprises the preliminary steps of: a1. shaping a pasty composition of a dielectric material, a binder and a solvent into a sheet having a predetermined size and thickness, and a2. drying said sheet to obtain said unsintered dielectric sheet.
 9. An improved method according to claim 7, wherein said step (a) comprises the steps of: a1. printing, on said unsintered dielectRic sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals; a2. printing, on the structure resulting from step (a1), a first dielectric layer having predetermined holes therethrough; a3. printing, on the structure resulting from step (a2), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes; a4. printing a second dielectric layer on the structure resulting from step (a3), exposing said cathode sets; a5. printing, on the structure resulting from step a4, said anode sets and third wires connected thereto and to be connected respectively to said anode terminals; and a6. printing a third dielectric layer on the structure resulting from step (a5), exposing said cathode sets and said anode sets.
 10. An improved method according to claim 8, wherein step (a) further comprises the steps of: a3. printing, on said unsintered dielectric sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals; a4. printing, on the structure resulting from step (a3), a first dielectric layer having predetermined holes therethrough; a5. printing, on the structure resulting from step (a4), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes; a6. printing a second dielectric layer on the structure resulting from step (a5), exposing said cathode sets; a7. printing, on the structure resulting from step (a6), said anode sets and third wires connected thereto and to be connected respectively to said anode terminals; and a8. printing a third dielectric layer on the structure resulting from step (a7), exposing said cathode sets and said anode sets.
 11. A method of manufacturing a multiple-digit gaseous discharge display device comprising the steps of: a. forming an electrode substrate on which cathodes and anodes are arranged by a1. multilevel-printing, on an unsintered dielectric sheet, a plurality of sets of cathodes for respective digits to be included in said display device, a plurality of sets of anodes associated respectively with said cathode sets, a plurality of cathode terminals to be connected to respective cathodes of said cathode sets, a plurality of anode terminals to be connected to respective anodes of said anode sets, a plurality of wires for interconnecting said cathode terminals to said cathodes, a plurality of wires for interconnecting said anode terminals to said anodes, and a plurality of unsintered dielectric layers, to thereby provide an unsintered multilayer electrode structure; and a2. sintering said multilayer electrode structure to provide a sintered electrode substrate; b. locating, on said electrode substrate, a partition plate having a plurality of spaced openings corresponding individually to the display sections of said electrode substrate including respectively said cathode sets therein so as to define respective discharge spaces; c. locating, on said partition plate, a front plate which is transparent at least at those portions opposite to the respective display sections; d. sealing gastight the outer periphery of the laminate structure consisting of said electrode substrate, said partition plate and said front plate; and e. evacuating said laminate structure and introducing a discharge medium into said discharge spaces.
 12. An improved method according to claim 11, wherein said step (a1) compriSes the steps of: a1-i. printing, on said unsintered dielectric sheet, said cathode terminals, said anode terminals, and first wires to be connected respectively to said cathode terminals; a1-ii. printing, on the structure resulting from step (a1-i), a first dielectric layer having predetermined holes therethrough; a1-iii. printing, on the structure resulting from step (a1-ii), said cathode sets and second wires connected respectively to the cathodes thereof, while electrically connecting respectively said second wires which are connected to the corresponding cathodes between said cathode sets to said first wires through said holes; a1-iv. printing a second dielectric layer on the structure resulting from step (a1-iii), exposing said cathode sets; a1-v. printing, on the structure resulting from step a1-iv, said anode sets and third wires connected thereto and to be connected respectively to said anode terminals; and a1-vi. printing, a third dielectric layer on the structure resulting from step (a1-v), exposing said cathode sets and said anode sets.
 13. A method of manufacturing a multiple-digit display device comprising the steps of: forming an electrode substrate by multilevel-printing, on a dielectric substrate through dielectric layer, a plurality of sets of cathodes of predetermined pattern constituting a plurality of display sections respectively and a plurality of sets of anodes associated with said plural sets of cathodes respectively; disposing, on said electrode substrate, a partition plate having a plurality of spaced openings corresponding individually to said display sections so as to define the respective discharge spaces; disposing, on said partition plate, a front plate which is transparent at least at those portions opposite to the respective display sections; sealing gastight the outer periphery of the laminate structure consisting of said electrode substrate, said partition plate and said front plate; evacuating said laminate structure and introducing a discharge medium into said discharge spaces; and wherein said dielectric substrate and said dielectric layers are initially unsintered and are simultaneously sintered before the evacution of said laminate structure. 